Tweets dating to 2011 and 2012 from the then-18-year-old's account included a gay slur, anti-gay comments and a joke with racist undertones.
On Sunday night, Turner issued a statement about the matter.
"There are no excuses for my insensitive and offensive language on Twitter," Turner, now 25, said. "I am sincerely sorry for those tweets and apologize wholeheartedly. I believe people who know me understand those regrettable actions do not reflect my values or who I am. But I understand the hurtful nature of such language and am sorry to have brought any negative light to the Nationals organization, myself or the game I love."
In his own statement, Nationals general manager Mike Rizzo said the tweets were "inexcusable" but added that Turner "has been a good teammate and model citizen in our clubhouse, and these comments are not indicative of how he has conducted himself while part of our team."
Newcomb's name gained a bit more fame Sunday afternoon, when he fell one batter short of a no-hitter in the Braves' 4-1 win over the Los Angeles Dodgers. Shortly after the best performance of Newcomb's young MLB career, a Nats fan account drew attention to the left-hander's tweets.
One tweet included a racial epithet that was part of a rap lyric, and several others contained gay slurs. The tweets in question date to when Newcomb was an 18-year-old in 2011 and 2012.
Newcomb apologized and expressed regret over his tweets, and Major League Baseball announced that the league's inclusion ambassador, Billy Bean, will meet with Newcomb this week.
A nearly identical situation occurred earlier this month involving Milwaukee Brewers reliever Josh Hader, who has since apologized both publicly and to his teammates, been cheered by the hometown Milwaukee fans and been booed on the road.